1. Field of the Invention
The present invention concerns a procedure for detection of the information of a received signal, as well as an electric circuit for implementing the procedure. Preferentially, the invention will serve to estimate a binary information item in a received signal modulated by frequency shift-keying (FSK).
2. Related Art
Various circuits for the reception of signals modulated by frequency shift-keying (FSK) are already known. The traditional incoherent circuits accumulate the energy of the received signal in each case for one bit period on the two frequencies F.sub.0 and F.sub.1, which represent the two binary symbols `0` and `1.` The frequency which, in each case, has the higher signal energy, provides the estimation value of the corresponding information symbol. These classical receivercircuits are explicitely described, e.g., by John M. Wozencraft and Irwin M. Jacobs in the book Principles of Communicatons Engineering, John Wiley and Sons, New York, 1965. These known circuits are theoretically optimal; however, in their practical application, they are very susceptible to non-ideal characteristics of the oscillators and filters, as well as deviation of broadcast frequencies from their ideal values.